Blue-fluorescent dyestuffs



Patented Jan. 1, 1952 UNITED STATES PATENT OFF-ICE 2,581,057BLUE-FLUORESCENT DYES'I'UFFS Walter Stanley Earl Krahler,

signers to E. L'du Pont de Nemours pany, Wilmington, Del.

ware

No Drawing. Original application Valentine Wirth, Woodstown, N. J.,. and

Wilmington, Del; as- & Coma' corporation of Dela- October 15,

1948, Serial No; 54,814. Divided and this ap plication October 25, 1949,Serial 2 Claims.

No, 54,814, filed 00170- zoyl nuclei with alkoxy groups;

It is an object of this invention to provide new cellulose-substantive,blue-fluorescent dyestuffs, which are useful particularly for impartingwhiteness to textile materials and related cellulosic fibers. Other andfurther important objects of this invention will appear as thedescription proceeds.

In copending application Ser. No. 29,664 it is taught that4,4-dibenzoyl-diamino-2,2'-disulfostilbenes which carry in each benzoylring two alkyloxy radicals'in the positions 3,4 are substantive tocellulose and are characterized particularly by a pronounced bluishfluorescence, when illuminated by ultra-violet light. Thus, thecompounds are characterized tby absorption of light in theultra-violetspectrum, with at leastone absorption maximum within theregion o-f 3000to 4000 angstrom units. When cellulosic material, for instance textilefabric or paper, is treated with an aqueous solution of one of thesecompounds and then exposed to ultra-violet radiation, the cellulosicmaterial glows with a bluish fluorescence.

We have now found that whitening agents of even greater potency areobtained by selecting for the purpose a bis-benzoylamino-stilbenedisulfonate carrying in each benzoyl nucleus 3 methoxy groups, which aredisposed in positions 2,4,5, the position of the CONE group beingcounted as 1, and the benzoyl radical being free of other substituents.Expressed in different words, we have discovered new and superiorbluefluorescents in a limited group of compounds characterized by thefollowing structure:

HaCO

division from our I30 and 2,497,131, respectively,

is essentially No.v 123,542

both issued on February 14, 1950.

Without limiting our invention, the following examples are given toillustrate-our preferred mode of procedure. Parts mentioned are byWeight.

Example 1 A mixture of 25 parts of 4,4'-diamino-stilbene-2',2'-disulfonic acid, 36 parts of 2,4,5-trimethoxybenzoic acid, 14.1parts of phosphorus oxychloride and 150 parts of pyridine is heated atreflux for minutes. At the end of this time the reaction completey'asshown by treatment of a small portion of'the reaction mixture with coldnitrous acid and alkaline R-salt; a purple 'color indicates incompletereaction. The hot mixture is drowned into 1000 parts-of water and madejust alkaline with 19.5 parts of sodium hydroxide. The drowned productis treated with 100 parts of salt, cooled to 25 C., filtered, Washedfree of excess alkali with 5% salt solution and dried. The pale tanproduct, sodium-4,4-bis(2,4,5 trimethoxy benzoylamino) stilbene 2,2disulfonate, is substantive. to cellulosic fiber from an aqueous bathand imparts thereto a strong blue fluorescence.

Example 2 [Using a procedure as described in U. S. Patent No.2,497,131.]

A mixture of 25 parts of 4,4'-diamino-stilbene- 2,2'disulfonic acid, 32parts of 2,4,5-trimethoxybenzoic acid, 81.1 parts ofdiethyl-cyclohexylamine, 217 parts of xylene and 43 parts of toluene isdistilled, approximately 72 parts of distillate being taken ofi so as toremove traces of water. The mixture is cooled to 100 C., 10 parts ofphosphorus oxychloride are added and the resultant slurry is heated atreflux for 2 hours. This is followed by two additions of 1.7 parts andone addition of 0.8 part of phosphor-us oxychlo- OCH;

OCH:

ride, each of which is followed by 1 hours reflux. The mixture isrefluxed for 2 hours longer, cooled to below C., diluted with 500 partsof water and steam distilled with addition of a suflicient amount ofsodium hydroxide to release the diethyl cyclohexylamine from its salts.Practically all the xylene, toluene and diethyl cyclohexylamine arecontained in the oil layer of the distillate. After cooling the mixture,the product is filtered, washed with brine and dried. The product isidentical with that obtained in Example 1.

The product in' the above two examples has been isolated as the sodiumsalt of the sulionic acid groups. lieu of sodium hydroxide, the productmay be obtained as the di-potassium sulionate. Isolation as the freedisulfonic acids can be effected by acidification of the condensationmass, and the products thus obtained may be reacted with ammoniumhydroxide or any suitable organic or inorganic base, to yield thecorresponding salt.

Evaluation of the product of Examples 1 and 2 above on textile fiber hasshown it to be a bluefiuorescent dye capable of imparting a strongerwhitening efiect to cellulosic fibers than other By using potassiumhydroxide in weights of the particular substances required to achieve acertain degree of whitening assumed as standard.

Study of the above data shows the superiority on a weight basis of thenew compounds of this invention as whitening agents over thosepreviously disclosed.

In addition to producing a whitening eiiect upon textile material, ournovel compounds may also be used for various other purposes wherefluorescence or absorption of ultra-violet light is desirable, forinstance to achieve fluorescent efiects in costumes or stage settings,to achieve novel efiects onphotographic paper, as ultraviolet filterswhen impregnated on cellulosic fibers used for wrapping materials, etc.

We claim as ourinvention:

l. A compound of the general formula OCHa , I WQGONHQCMH NHGOQM.

CH: 03M 80M CH3 compounds of the benzoylamino-stilbene-disulionic acidgroup which have previously been disclosed in the patent literature.

The following comparisons were made on dyeings of various fluorescentson paper, by using the beater-dyeing technique and judging the dyedpaper in diffuse daylight:

General formula:

The column marked Grams shows the wherein M stands for a member of thegroup consisting of hydrogen, the alkali-metals and ammonia.

2. 4,4'-bis(2,4,5 trimethoxy benzoylamino)- stilbene-2,2-di(sodiumsulfonate) WALTER VALENTINE W'IRTH. STANLEY EARL KRAHLER.

Z CMH NMOQY I OzNB OzNS REFERENCES CITED UNITED STATES PATENTS Name DateEberhart Apr. 26, 1949 Number

